泥石流频发区不同土地利用类型下土壤分形维数与理化性质的关联度

Correlation degree analysis of soil fractal dimension and physical and chemical properties under different land use types in debris flow prone areas

为综合评价泥石流频发区不同土地利用类型下土壤的结构稳定性,本研究以蒋家沟为例,选取耕地、草地、林地为研究对象,裸地作为参照,基于分形理论分析了不同土地利用类型下土壤的分形特征,利用主成分分析方法,分析了影响土壤结构稳定性的主要影响因子,同时利用关联耦合度方法构建了土壤分形维数与理化性质间的耦合模型。结果表明,不同土地利用类型下土壤的分形维数介于2.71~2.75,0.5~2 mm土壤颗粒含量决定了不同土地利用类型下土壤的分形维数;土壤颗粒的分形维数与土壤碱解氮、容重、有机质含量显著相关,两者之间属于中等关联,土壤理化性质对分形维数的影响大小依次为容重>碱解氮>有机质;分形维数与理化指标的系统耦合度属于弱协调,未达到最佳状态;不同土地利用类型的系统耦合协调程度按大小排序为林地>草地>耕地>裸地。研究结果表明,增加植被覆盖和减少人为扰动有利于稳定的土壤结构形成。研究结论可以为流域植被恢复及土壤结构特征描述提供一定的理论依据。

In this study,we used Jiang Jia River as an example to comprehensively evaluate soil structural stability of different land use types.Cultivated land,grassland,forest land,and bare land were chosen as research materials.Based on fractal theory,the fractal characteristics of soil under different land use types were analyzed,the main influencing factors of soil structural stability were analyzed using the principal component analysis method,and the coupling model between fractal dimension and physical and chemical properties of soil was constructed by means of correlation coupling degree method.The results showed that the fractal dimension of soil under different land use types ranged from 2.71 to 2.75,and the soil particle content of 0.5~2 mm determined the fractal dimension of soil under different land use types.The fractal dimension of soil particles was significantly correlated with the content of alkaline nitrogen,bulk density,and organic matter in soil,and the physical and chemical properties and fractal dimension were moderately correlated.The effect of soil physical and chemical properties on the fractal dimension was bulk density>alkaline nitrogen>organic matter.The coupling degree between fractal dimension and physical and chemical indexes of soil was weak,and they did not reach the optimal state.The degree of system coupling coordination of different land use types was sorted by size as follows:forestland>grassland>cultivated land>bare land.It was beneficial to increase vegetation cover and decrease anthropogenic disturbance for the formation of stable soil structure.These findings can provide some theoretical basis for vegetation restoration and soil structure description in watersheds.